1. Field of the Invention
The present invention relates to a black matrix for color filters or TFT arrays to be used for e.g. flat panel displays represented by color liquid crystal display devices.
2. Discussion of Background
Flat panel displays represented by color liquid crystal display devices are more actively used as information devices, as monitor displays for notebook computers and as dynamic image displays for TV image. Particularly in recent years, the TV broadcasting has been decided to be digitized, and accordingly, it is believed certain that color liquid crystal display devices will be used as TV receivers in future instead of cathode ray tubes which are widely used at present.
In these color liquid crystal display devices, a color filter substrate or the like to be used is provided with a black matrix so as to increase display quality such as display contrast of the image.
The black matrix shades the periphery of the display portion of each color picture element of three primary colors R, G and B adjacent to each other of a color filter to prevent bleeding of each color and color mixture is thereby prevented, and the black matrix is commonly used to improve the contrast of the color display and to increase the display quality.
As a material for the black matrix, a metal chromium film is usually used from such reasons that film formation is easy and production is easily carried out in a color liquid crystal display devices production process, a strong film can be formed, it is stable as a liquid crystal display panel and is highly reliable, and adequate light shielding properties can be obtained. Further, in order to make the black matrix low-reflecting, a method of constituting a multi-layer structure is employed wherein e.g. a chromium oxide film, a chromium oxynitride film or a chromium oxycarbide film is deposited either or both on and below the metal chromium film. The metal chromium film and the like are used to form a black matrix by forming patterns utilizing known photolithography.
The metal chromium film and the like are commonly used since the degree of light shielding is high and a high light shielding property with which the optical density (OD value) at the visible light region becomes at a level of 4.5 is relatively easily obtained, even if they are relatively thin films as mentioned above, the variation with time is slight, and fine patterns can be formed by conventional photolithography. However, a large amount of labor and cost are required for handling of an etchant, treatment and control of the effluent, when patterning on the metal chromium film and the like is carried out.
On the other hand, as a substrate for the metal chromium film, employment of a photosensitive resin film is expected for a black matrix for liquid crystal display devices. However, a film thickness at a level of from 1.5 to 2.0 xcexcm will be necessary to obtain a light shielding property at the same level as a chromium film. Since the thickness of each of colored films of R, G and B is at a level of from 1.0 to 1.5 xcexcm, the overlaid portion which is formed to prevent bleeding at the periphery of each picture element has a height of from about 2 to about 3 xcexcm, which deteriorates flatness of a color filter. Further, the resin black matrix is thick, whereby a pattern may drop out during development or it may overhang in photolithography process, and accordingly it tends to be difficult to form a black matrix with a high precision.
In order to overcome the above problems, it has been proposed to use a Nixe2x80x94Mo type metal as a substitute for the metal chromium film (JP-A-9-243801, JP-A-10-301499, JP-A-11-142617). However, of films as specifically disclosed in these literatures, the etching rate is significantly different from the etching rate of a chromium film, whereby large-scale renovation of production apparatus or change of etching conditions is required to employ such films.
To overcome the above problems, the present invention provides a black matrix for liquid crystal display devices which comprises at least one light shielding layer, wherein the light shielding layer substantially comprises the following components:
The present invention further provides a black matrix for liquid crystal display devices which comprises at least one light shielding layer, wherein the light shielding layer substantially comprises the following components:
The present invention further provides a black matrix for liquid crystal display devices which comprises at least one light shielding layer, wherein the light shielding layer substantially comprises the following components:
The present invention still further provides a black matrix for liquid crystal display devices which comprises at least one light shielding layer, wherein the light shielding layer substantially comprises the following components:
According to the present invention, a black matrix, a production line for which can easily be substituted with that for patterning of a black matrix made of a metal chromium film, which is resistant to e.g. an alkali liquid or an acid to be used in production process of a color filter, and which is highly reliable, can be obtained.